Prior to the present invention a wide variety of silicone surfactants has been reported in the literature for use in the preparation of flexible polyureathane foams. However, the currently used flexible foam surfactants derived from either hydrolyzable or non-hydrolyzable technology typically do not offer both high potency and flat foam breathability profiles in the same polymeric product.
Improving the potency of the surfactant is, of course, desirable from a performance standpoint since equivalent foam properties can be obtained using less of the costly surfactant. Surfactants which give flat foam breathability profiles are desired since a customer should have the option to change the amount of a surfactant without drastically changing the breathability of the final foam product. While some surfactants impart excellent potency to foams they suffer from a significant drop in the foam's breathability profile as the surfactant level is increased. In contrast, other surfactants may give a flatter breathability profile but are less potent. The typical non-hydrolyzable silicone surfactant structures utilized today represent a trade off between high potency and flatness of the foam's breathability profile.
It has been also observed that none of the siloxane compositions disclosed to date in the literature for use as flexible foam surfactants has pendant cyclic siloxane rings which are attached to the siloxane backbone through Si--CH.sub.2 CH.sub.2 --Si-- linkages. It has been noted that polymers containing this particular molecular configuration provide excellent surfactants which possess the ability to impart both potency and flat breathability profiles to flexible ureathane foams. Accordingly, it is possible to use a lesser amount of the surfactant with the accompanying economic advantages in the preparation of such flexible foams.
U.S. Pat. No. 2,834,748 which issued May 13, 1958 to F. Bailey and which is assigned to Union Carbide Corporation, is directed to the general area of hydrolyzable silicone surfactants and discloses and claims compositions of hydrolyzable siloxaneoxyalkylene block copolymers. These hydrolyzable structures however, contain Si--O--C linkages at the attachment point of the polyether pendant to the silicone backbone.
In Japanese Pat. No. 50/4199 which issued in 1975 to Shin-Etsu, a terpolymer is disclosed which was prepared with a siloxane backbone having pendant oxyalkylene and siloxane groups. The adducts disclosed in this patent, however, do not contain any pendant cyclic siloxanes. Moreover, when such terpolymers were tested under the conditions set forth in the present invention, they failed to stabilize polyurethane foams and exhibited poor performance characteristics.
Cyclic siloxane rings have been incorporated into the siloxane backbone of siloxane chains. One example described in the literature is an article by Mukbaniani, Chem. Abstracts 104: 207800x, in which a dimethylsiloxane chain is disclosed containing regularly occurring organocyclopentasiloxane units. Structures containing a T unit (MeSiO.sub.3/2) may loop back to the T to form a cyclic siloxane fragment at the end of the siloxane chain. In both of these types of structures the cyclic siloxane ring is attached to the backbone through Si--O--Si linkages and not through Si--CH.sub.2 --CH.sub.2 --Si linkages.
Cyclic siloxane rings have also been used as side chains in polydimethylsiloxane polymers. A Russian article by Esartiya in Chem Abstracts, 105: 153620p discloses polysiloxane structures where cyclic siloxane rings containing one T unit (MeSiO.sub.3/2) per ring are attached to a siloxane backbone through Q (SiO.sub.4/2) linkages to the T unit of the ring. These structures are very different from the instant invention in the manner the siloxane is attached to the backbone and in the composition of the ring siloxanes. The instant invention incorporates only D units instead of T units in the siloxane ring pendants and the rings are attached to the backbone through Si--CH.sub.2 --CH.sub.2 --Si linkages instead of the Si--O--Si linkages of the prior art polymers.
In Japanese Pat. No. 58/58519, 1983 which issued to Nihon Contact Lens Seizo K.K. there is described a block copolymer containing a siloxane backbone with both ally polyethylene glycol pendants and linear siloxane pendants. The block copolymer is used for contact lens. In this case the siloxane pendant is based on a silicone resin of the structure CH.sub.2 .dbd.CHSiMe.sub.2 (OSiMe.sub.2).sub.n OSiMe.sub.2 CH.dbd.CH.sub.2 where n is an intergral number. This resin contains two vinyl groups wich are capable of reacting with two different Si--H sites on the same or on different siloxane chains. Thus, this resin is capable of serving as a crosslinker between two siloxane chains.
Accordingly, one or more of the following objects will be achieved by the practice of the present invention. It is an object of this invention to provide novel siloxane polyether polymers containing pendant cyclic siloxane groups. Another object of the present invention is to provide polymers having pendant cyclic siloxane groups which are attached to a siloxane backbone through Si--CH.sub.2 --CH.sub.2 --Si linkages. A further object of this invention is to provide certain siloxane polyether surfactants which are useful in the preparation of polyurethane foams. Another object of this invention is to provide a process for the preparation of the siloxane polyether polymers and their use as surfactants in the preparation of foams. A further object is to provide surfactants which can impart to foams both high potency and flat breathability properties and accordingly can be employed in lesser amounts than known surfactants currently available. These and other objects will readily become apparent to those skilled in the art in the light of the teachings herein set forth.